Grantia is 'n genus van sponsdiere uit die klas van die Calcarea (kalksponse).
Spesies Grantia aculeata (Urban, 1908) Grantia arctica (Haeckel, 1872) Grantia atlantica (Ridley, 1881) Grantia beringiana (Hozawa, 1918) Grantia canadensis (Lambe, 1896) Grantia capillosa (Schmidt, 1862) Grantia comoxensis (Lambe, 1893) Grantia compressa (Fabricius, 1780) Grantia cupula (Haeckel, 1872) Grantia extusarticulata (Carter, 1886) Grantia fistulata (Carter, 1886) Grantia foliacea (Breitfuss, 1898) Grantia genuina (Row & Hozawa, 1931) Grantia glabra (Hozawa, 1933) Grantia harai (Hozawa, 1929) Grantia hirsuta (Topsent, 1907) Grantia indica (Dendy, 1913) Grantia infrequens (Carter, 1886) Grantia intermedia (Thacker, 1908) Grantia invenusta (Lambe, 1900) Grantia kempfi (Borojevic & Peixinho, 1976) Grantia kujiensis (Hozawa, 1933) Grantia laevigata (Haeckel, 1872) Grantia mexico (Hôzawa, 1940) Grantia mirabilis (Fristedt, 1887) Grantia monstruosa (Breitfuss, 1898) Grantia nipponica (Hozawa, 1918) Grantia phillipsi (Lambe, 1900) Grantia primitiva (Brøndsted, 1927) Grantia ramulosa (Dendy, 1924) Grantia scottia (Jenkin, 1908) Grantia singularis (Breitfuss, 1898) Grantia socialis (Borojevic, 1967) Grantia strobilus (Haeckel, 1872) Grantia stylata (Hozawa, 1929) Grantia tenuis (Urban, 1908) Grantia transgrediens (Brøndsted, 1931) Grantia tuberosa (Poléjaeff, 1883) Grantia uchidai (Hozawa & Tanita, 1941) Grantia vosmaeri (Dendy, 1893) Grantia waguensis (Hozawa, 1940)